1. Technical Field
This application generally relates to system monitoring, and more particularly to techniques used in connection with monitoring and management of data storage and other systems.
2. Description of Related Art
Computer systems may include different resources used by one or more host processors. Resources and host processors in a computer system may be interconnected by one or more communication connections. These resources may include, for example, data storage devices such as those included in the data storage systems manufactured by EMC Corporation. These data storage systems may be coupled to one or more host processors and provide storage services to each host processor. Multiple data storage systems from one or more different vendors may be connected and may provide common data storage for one or more host processors in a computer system.
A host processor may perform a variety of data processing tasks and operations using the data storage system. For example, a host processor may perform basic system I/O operations in connection with data requests, such as data read and write operations.
Host processor systems may store and retrieve data using a storage device containing a plurality of host interface units, disk drives, and disk interface units. Such storage devices are provided, for example, by EMC Corporation of Hopkinton, Mass. and disclosed in U.S. Pat. No. 5,206,939 to Yanai et al., U.S. Pat. No. 5,778,394 to Galtzur et al., U.S. Pat. No. 5,845,147 to Vishlitzky et al., and U.S. Pat. No. 5,857,208 to Ofek. The host systems access the storage device through a plurality of channels provided therewith. Host systems provide data and access control information through the channels to the storage device and storage device provides data to the host systems also through the channels. The host systems do not address the disk drives of the storage device directly, but rather, access what appears to the host systems as a plurality of logical disk units. The logical disk units may or may not correspond to the actual disk drives. Allowing multiple host systems to access the single storage device unit allows the host systems to share data stored therein.
In connection with a data storage system as well as other systems, data may be gathered to monitor the system performance. At defined time intervals or polling intervals, data, such as various counters or other metrics, may be gathered in order to gauge system performance. Complex systems, such as data storage systems, may include many components about which data is obtained at each sampling time. As the number of components increases, the amount of data which is gathered at each polling interval increases accordingly using more time and resources of the system to obtain the data about the system. Thus, it becomes more difficult to sample data at a high rate of frequency as the complexity of system increases.
One existing technique for evaluating the gathered data determines changes in counter values relative to the time difference between samplings. For example, an average value of a counter may be determined for a polling interval by determining a change in each counter value relative to the change in time since the last set of sample data was obtained. Use of the average values provides information regarding average performance during the polling interval but does not provide more detailed information about system activity and performance occurring within the polling interval. For example, if data is sampled every 10 minutes, counter values determined using the foregoing existing technique reflect an average for the 10 minute time period. The average counters do not provide further detail or breakdown as the activity level may vary within the 10 minute interval. If a burst of activity occurs during the first 5 minutes of the sampling period, the data gathered only provides an average and does not provide more detailed information regarding what actually occurred in the system during the first 5 minutes of the sampling period when activity may have been at its peak for the sampling period. Using the existing technique of averaging, the polling interval rate may be decreased to 5 minutes to collect such data. However, it may not be desirable or even possible to increase the polling frequency rate to obtain such information depending on the complexity of the system being monitored. Furthermore, existing techniques to collect the added data associated with increased polling frequency may interfere with normal system activity as well as create very large data files that may be cumbersome to process.
Thus, it may be desirable to utilize a technique for identifying an activity level distribution providing information about system performance during a polling interval independent of the polling interval time. The technique may provide information associated with varying levels of activity occurring during a polling interval.